Knife grinder



T. C. SHEEHAN KNIFE G RINDER Filed Aug'. 3l. 1921 2 Sheets-Sheet 1 l NT R B WMM/E y ep, w ww Hman? T. C. SHEEHN KNIFE GRINDER Filed Aug' 31 1921 2 Sheets-Sheet 2 I /N VENT ze @wwf m BYKWW ATTORNEY Patented Sept. 16, 1924.

UNITED STATES PATENT OFFICE.

THOMAS CORNELIUS SHEIEIHAN,` -OF [UPPER MONTCLAIB, NEW JERSEY, ASSIGNOR TO DURHAM DUPLEX RAZOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

KNIFE GRI'NDER.

Application led August 31, 1921. Serial No. 497,191.

To all whom ,it may cmwem: e v

Be it known that I, THOMAS CORNELIUS SHEEHAN, a citizen of the United States, residing at Upper Montclair-'countyvvof Essex, and State of New Jersey, have invented a new and useful Improvementv in Knife Grinders, of which the following is a specification.

This invention relates to an improvement in knife grinders, particularly to those adapted to grind table knives.

Table and other knives are customarily forged with longitudinally and transversely tapered blades the opposite surfaces of which are then ground, one after the other,

in the planesy of the opposite surfaces as,l forged. This grinding operation does not' produce a knife edge of equal thickness throughout its length because the surfaces are farther apart adjacent the bolster than they are at the point, vand these surfaces, therefore, both before and after grinding, lie in planes which intersect the median plane of the blade beyond but not equidistant from its edge throughout its length, the point on the line of'intersection nearest the bolster being farthest from the blade edge beca-use the latter is thickest at this point. Further grinding operations .are therefore necessary toreduce the ground blade edge to approximately uniform thickness. These further operations are usually hand operations, and in any event the result effected is a blade flat at the point but more or less convex near the bolster.

It has been' discovered thlat by temporarily distorting or twisting a longitudinally and transversely tapered blade to successively cause its surfaces to be ground in planes which intersect the median plane of the blade equi-distant from its edge throughout its length, a blade having an edge of perfectly uniform thickness throughout its length can be produced, without hand or machine edge reducing operations, and that a blade so ground presents a better appearance and has improved efficiency as a cutting instrument.

The invention consists in certain constructions and combinations which will be hereinafter fully described and then specitcally pointed out in the claims hereunto appcn ed.

-ln theV accompanying drawings, which form a part of this specification and in Fig. 2is alongitudinal sectional elevation,

on an enlarged scale, of one of the knife supporting and'grinding devices shown in Fig. 1, Fig. 3 is a-.plan view of a part of the knife supporting and grinding devices shown in Fig. 1, Fig. 4 is 'a perspective view, on an enlarged scale, of a knife and holder as used in the structure shown in Fig. 1, and Figs. 5, 6 and 7 are respectively crosssectional and fragmentary views taken on the lines 5 5, 6 6 and 7 7 in Fig. 4.

The method of grinding employed in the present invention consists in ltemporarily distorting a longitudinally and transversely tapered lade to cause one surface thereof to lie in a plane which intersects the median planeA of the blade equi-distant from its edge throughout its length, then grinding the surface yso disposed, then temporarily distorting the blade in likemanner in the opposite direction, land then grinding the opposite'surface. Asthe method is ordinarily employed, a plurality of knife blades are arranged in a circle andtemporarily distorted, and the Whole series rotated so that their exposed surfaces are ground by a trate one embodiment of the invention, 8

indicates generally what is known as a Blanchard grinding machine the particular construction of which is well known and lies wholly outside the present invention.

This grinding machine is as usual provided with a rotating annular grinding Wheel 9 and with a circular work holder or table l0 which also rotates but at' a lower speed than the grinding wheel.

For the purpose of temporarily distorting and holding a plurality of knife blades on the table 10, a corresponding nuniber of magnetic devices are rovided, one half of which may be rightand and the other half4 left-hand; that is to say, one half of these devices may be adapted to distort blades in one direction to prepare them for grinding one surface, and thexother half adapted to distortl other-htten lin the opposite direction tol prepare them for the the opposite surfaces. With this exception, all of these devices are alike, and therefore a description of one vwill sufiice for a description of all.

The annular magnetic chucks ordinarily employed on rinding machines have been found unsuita le for present purposes because they are inherently incapable of distorting knife blades. The present device is therefore provided with a plurality of individual knife supports or holders 11, each havingv a plurality of electromagnets 12 connected in series. The operative ends of the magnet cores terminate in a recess 13 sunk in the upper face of the support or holder 11, nand are of different an ularity as clearly shown in Figs. 5, 6 and The recess 13 is Anot the shape of a lmife blade as forged but as temporarily distorted by the magnets to cause its upper or exposed surface to lie in a plane which intersects the median plane of the blade equi-distant from its edge throughout its length. In other words, the cross-sectional form of the recess is such that when the magnets pull a blade down, twisting it by reason of the different angularity of the magnet ends, the

grinding of blade rests solidly on the bottom of the just dii recess, with ilts exposed surface but slightly above the upper surface of the support 11. As shown in igs. 1 and 3, the supports 11 vare bolted to the table 10 and arranged in a circle about the table axis.

By an inspection of Figs. 1 and 3,- it will be understood that the grinding wheel 9 sweeps across the entire exposed surfaces of the temporarily distorted blades4 as the grinding wheel and table rotate at different speeds, grinding twelve right-hand surfaces and twelve left-hand surfaces. When this operation is completed, half the blades, then finished, are removed from their supports, the other half reversed in the supports-just vacated, and twelve ung'round blades placed in the supports from 'whichA transfer has been made. The opposite surfaces of partially ground blades andthe initial surfaces of the `unground blades Aare then ground in a single operation. When bothy surfaces of a blade have been thus ground, and the blades return to" their normal undistonted condition, the ground Asurfaces are dat and lie in planes which intersect the median plane of the l from its edge throughout its len h, it bein linde lH t that 'the 'tion 0 the line 0 intersection depends upon the keenness it is desired to give the cutting edge, and that in any c it sandrths ci an inch# By sc grinding the blades, the nity heretofore existing for ee reducing operations is avoided and en edge of uniform thickness is produced on a blade presenting e. uni

voperating faces of different an blade equi-distant is a matter of a few thou.-l

tion is carried into effect, within the Scope -of the claims. The invention, therefore, is

not to be restricted to the precise details of the structure shown and described.

What is claimed is:

1. In a grinder, the combination with a support, of means coacting with said support and adapted to twist a longitudinally and transversely tapered blade on said support to cause one surface thereof to lie in a plane which intersects the median plane ofthe blade equi-distant from its ed e substantially throughout its length,van acoacting rinding device adapted to act' 4on the su ace so disposed.

2. In a grinder, the combination with a support provided with a recess in one: of its faces,l of means.` coacting with said support at said recess and adapted to twist a longitudinally and transversely tapered blade in said recess to cause one surface thereof to lie in a plane which intersects the median plane 'of the blade equi-distant from its edge substantially throughoutl its len h and lies slightly' beyond the tace of sai support at said recess, and a coaoting grinding device adapted to act on the surface so disposed.

3. In a fgrinder, the combination with a sup ort, o a magnetic device coaoting with sai support and having a distorted Operating face adapted to twist a longitudinally `and transversely tapered blade on said support to cause one surface thereof Ato lie in a plane which intersects the median plane of the blade equi-distant from its ed e sub stantially throughout its length, an -a coacting rinding device adapted to act on the su ace so disposed. e

4. In a grinder, the combination with a. support, vof a series of electro-magnets coacting with said support and havin adapted to twist a longitudinal y and transversely tapered blade on said support to cause one surface thereof to lie in a lane which intersects theJ median plane o the blade equi-distant from its edge substantially throughout its length, an a coactmg rinding device adapted to act on the surace so disposed.

`5.. In a grinder, support provided its faces, coactng with said support at the bottom of said recess and having operatin faces of different angularity and adapte to twist a longitudinally and transversely tapered blade in said recess to cause one ace thereof to lie in a plane which inte the median plane of the blade equi-distant from its edge substantially throughout its the combination with a larity an with a recess in one ofof a series of electro-magnets4 meme? length and lies slightly beyond the face of Support to cause one surface thereof to lie said support et seid recess, and a coacting in a plane, and a coacting grinding de vice grinding device adapted to aci*l on the suradapted to act on the surface so disposed. 10 face so disposed. In testimony whereof, havesigned my 5 6. In a nder, the combination with a name to this specification.

support, ogxilneans coasting with said support and adapted Ito twist an article on said THOMAS CORNELIUS SHEEHAN. 

